Telephone-exchange system and apparatus.



A s. B.- WILLIAMS.- Y TELEPHONE EXCHANGE SYSTEM AND APPARATUS'. YAPPLIOATIQLL FILED DBo. 2o, 1909. I z 1,097,204:g Patented May 19,1,914.

'UNTTED sTATEs PATENT oEEroE..

SAMUEL B. VILLIAMS, OF vNEWT YORK, N. Y., ASSIGNOR T WESTERN ELECTRICCOMPANY, 0F NEW YORK, N. Y., A CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM AND APPARATUS.

Specification .of Letters Patent. l

Patented May 19, 1914.

Application led December 20, 1909. Serial No. 533,986.

b all echo/a izm f1.1/ concern:

Be it known that l, SAMUEL'B. WILLIAMS, citizen of the United States,residing at New York. in the county of New York and State-ot New York,have invented a certain new and useful Improvement in Telephone-Exchangc System and Apparatus, of which the following is in full, clear,concise, and exact description.

This invention relates to telephone exchange syst-ems, and particularlyto telephone exchange systems which employ automatic ringing forsignaling purposes and which are equipped with trunk lines leading toprivate branch exchanges, chief operators desksl and like positions.

As applied to ordinary subscribers lines automatic or keyless ringinghas proven eininently satisfactory, but when employed in signalingbetween olices connected by trunk lines, for instance between a centraloilice and a private branch exchange, or between one operators positionand anothers, such as between an answering operatorand a chief operatorsdesk. the method of applying automatic ringing has been found to possess.an inherent defect which manifests itself `in the form of anobjectionable click in the ear of the answering operator upon thedepression of the listeningl kcy in response to a` call, since shethereby brings her telephone directlyinto- :,i-circuit upon whichringing current is being impressed, which ringing current is thereuponcut oil". hut not before it has given her the disagreeable clickreferred to. due to the action of the central oflice mechanism in.ytransferring the trunk leads from the source of ringing current to theSource of battery current upon the depres- 0 sion .of the listening key.This objection is not met with in signaling an ordinary subscriber forthe reason that the mechanism at the central oflice operates anddisconnects ringing current. from the line and substitutes talkingcurrent therefor in the internal between the time he removes hisreceiver from its hook and the time he places it to his ear. It is verydesirable that this objectionable 4feature be eliminated. 59.; Theypresent invention hasA that purpose fas its object, and consists inproviding'a cir. cuit arrangement whereby upon the depression of thelistening key by the answering operator in response toaJ call., a relayis ineluded in the circuit and is adapted upon its energization to causethe disconnection of the ringing current from the line, and theactuation o means to thereafter include the operators telephone set incircuit7 thus providing for the inclusion of the telephone set incircuit after the ringing current has been disconnected.

More specifically the invention consists in providing a relay adapted tobe included in the ringing circuit upon the depression of the listeningkey and in its actuation to provide an increase in the strength of theringing current to operate a marginal relay at the calling board toshift the leads from a source of ringing current to a source of directcurrent. the consequent How of direct current causing the actuation of adirect current relay at the called position to include an ,operatorstelephone in circuit.'

The apparatus at the central oliice for signaling the wanted privatebranch exchange or'othei1 operator may comprise the usual apparatusemployed in 'automatic ringing and for the purpose of this invention itwill be sufficient to say that it consists of a source of alternatingcurrent and a source of direct current so connected with the lead to theringing circuit that the insertion of the plug will brim; about theactuation of means adapted to impress current from the alternatingsource upon the line for a certain interval. say two seconds. when it issucceeded by a silent period of say three seconds. during Which time thelead to the ringing circuit is connected to the battery source anddirect current is caused to pass out over the line in substitution ofthe alternating current. Should the listening key be depressed during asilent period, the means which coutrols the application or" ringingcurient is rendered active to bring about the disconnection of both ofsaid sources of current and incidentally to cause the leads to the trunkto bfconnccted to a source of battery current from the cord circuit.which holds up the relay which connects the operators telephone set incircuit.

l have illustrated my invention as embodied in a telephore exchangeequipped with a keyless autom'atic ringing cord circuit. but l do notwish to 'be understood as limiting myself to the precise form -drown.since any system wherein an intermwliate device arranged to he. opeatedby the ringing current to disconnect the same from the line andthereafter cause the inclusionco't a telephone in circuit would bewithin the scope of this invention.

The invent-ion will be more readily understood by reference to theaccompanying drawing, which is a diagram illustrating the invention asembodied in a telephone eX- change system and wherein is shown thekeyless automatic ringi "g cord circuit terminating in a plug connectionwith the jack` of a trunk leading to a desk operators position. i

The same letters of reference designate the same parts wherever they areshown.

The switchboard A is the calling board and the operator thereat forconvenience will be designated t-he A operator. The switchboard B is theanswering board and the operator thereat will be called the answeringoperator. Each trunk may terminate at the B or answering board in asignal actuating device as shown, which in the present instance is aring-down relay 26, and may also have connection with a plug foranswering the call. For clearness of illustration, however, the plug isomitted, as is also the plug which may be connected to t-he conductors4, 4, where they are broken off, to extend the call to a subscribersline terminating at the answering board. The dotted line indicates thedivision of the circuit between the exchanges, that to the left of theline being located at the switchboard A and that to the right beinglocated at the answering board, the trunk line being indicated by .thenumerals 4, 4a. A listening key is also provided individual to eachtrunk and is adapted upon its depression to close a circuit for a magnetcommon to all the trunks which upon its energization disconnects theringing current from the line and thereafter brings aboutv the actuationof a relay adapted to include an operators telephone set in circuit.

Referring to the drawings the three limbs 1, Q, 3 of the cord circuit.at the A board terminate in a plug adapted for insertion into the jackof the trunk line 4, 4 which leads to the answering board B. This plugwhen inserted into the jack is arranged to close a circuit from` abattery 6 to the grounded sleeve of the jack and cause the illuminationof the supervisory lamp 7. A, relay 8 in the pathv of` the batterycurrent to the trunk line controls the illumination of this signal,being adapted upon its actuation, which occurs when the desk operatorhas answered the call, to close a shunt circuit comprising theresistance 18 and the conductor 9 about said lamp and thereby darken thesame, and alter-ward then the connection is taken down by the answeringoperator to again become armature to 'tall back, thereby removing theshunt and againl causing its illumination.

which is adapted 'for' `inert and allow its The relay 5 is provided withan armature 10 which is adapted to bc drawn up to close its cont-actupon the energization of said relay, the said armature being ,groundedFrom the grounded armature 10 a conductor 11 extends and branches at 12into multiple paths 13, 14 and unites again at 15, whence it continuesby conductor 1G to a relay 17, conductors 1G, 48, resistance 18 to abattery 19. relay Q0 as included in the branch circuit 13, the saidrelay being normally short-cireuited by `conductor 14, armature 24, itsback contact, conductor 21, its own ar1nature,'to point 15, where itunites with conductor 16. The relay 17, however, is adapted to respondto the current flowing in this circuit, and upon its energization toattract its armatures Q4, 25.

From the source of ringing current 22 a conductor 23 leads to the frontcontact of an armature 24 of relay 17, and when said armature isattracted, to the ring of the plug, adapted to register with the ring ofthe jack, and thence by way of conductor 4, through bridge 28includinigr a ring-down relay 26 and condenser 42, and back to ground byway of conductor 4, the tip o' the jack, the tip of the plug,conductor 1. armature Q5 and its fronbcontact to the grounded conductorQ7. The ring-down relay Q0 is responsive to alternating current in thiscircuit and is bridged across conductors 4, 4 through a condenser 4Q. Arelay 3S is'included in the ringing circuit Iiust traced, but ismarginal in operation and will not respond to the ringing currentapplied to the line by the 4apparatus 22. This relay is, however,adapted promptly to respond upon its inclusion in a direct currentcircuit.

At the answering board the usual listening key 29 is providedindividually to each trunk, a contact of the said key normallycompleting a circuit with conductor 30 leading to th arn'iature of thering-down relay *26 which is adapted when attracted' to close a holdingcircuit including a battery 49, for the illumination of lamp 32 in acircuit 'from battery 43 to ground at 44 to indicate to the operatorthat conversation is desired, the depression ci said key by the operatorin respending opening said circuit at contact of conductor 8O andextinguishing said signal. The listening key is connected withconductors 33, 33"* and upon its depression is adapted to extend thecircuit of line conductors 4, 4' to conductors 83, 33a. A bridge oiconductors 33, 33 is rendered non-conductive to battery current and isalso rendered ot relatively high impedance to the high frequency talkingcurrent by reason of the inclusion therein ot a condenser 35 of suitinmultiple with bridge 4o, including a low i non-inductive resistance 35a,the said path with the resistance 35a and a retardation coil 4l is arelay 36 adapt-ed to respond to directcurrent only, and to include anoperators' telephone set 37V in circuit with con- `ductors 33, 33a. Thisrelay will not respond to the alternating current adapted tooperate'relay 34 because of the inclusion of Y the impedance coil 41 inits circuit, and in addition the relay may be made sluggish in itsaction so as not to respond to short impulses. The purpose of theresistance 35a is to prevent an excess of current through the Winding ofrelay 36 should the operator depress the listening key during a silentinterval when direct current from the battery 22 is being inpressed uponthe line. Upon the' response of the called operator by the depression oflistening key 29, the relay 34 instantly closes at its armature contactthe low resistance path including the non-inductive resistance 35a andpermits of an adc quate increase in the flow of current in the circuitfor the operation of relay 38 in the circuit of the-A board. Thecondenser 50 bars the passage of direct current to the operatorstelephone set 37. The relay 38 con- -`trols at itsy armature contact ashort circuit of relay 20 and upon its excitation is adapted to attractitsarmature and open the short circuit, about said relay, therebycausing its energization, which relay thereupon operates and at itsfront contact closes a short circuit of relay 17, causing thedenergization of said relay, and the armatures thereof fall back andtransfer the connections of the trunk to the source of battery current40. This battery may be bridged across the cord circuit conductors 45,46 through the usual repeating coil- 47 and may be of say 24 volts.

The operation of the system of this invention is as follows: Assumingthe A operator has selected the jack connected with a desired trunk, sheinserts t-he plug therein. A circuit is now completed for theillumination of the lamp 7, and may be traced from battery 6 byiivay ofconductor 3, thesleeve strand of the plug which registers with thesleeve of the jack, to ground through a resistance, causing theyillumination of the signal 7 and the energization of relay 5. Itsarmature is thereupon attracted and closes a circuit from the groundedarmature 10, conductors 11, 14, armature 24a of relay 38, conductor 21`armature of relay 20, conductor 16, relay 17, conductors 16 and 48, tobattery 19. The relay 20 being thus short-circuited cannot operate. Therelay 17, however, is now energized and draws up its armatures 24, 25completing a circuit for applying ringing current to the trunk linewhich may be traced as follows:

from the grounded generator 22, conductor 23, relay 38, conductor 23,front contact of armature 24, conductor 2, ring of the plug ring of thejack, conductor 4, and through thebridgc 28 including condenser 42 andrelay 26 back to ground by Way of conductor 4a, tip of the jack, tip ofthe plug,

conductor 1, armature 25, conductor 27 to ground. The relay 38 isincluded in the circuit just traced, but since it is marginal inoperation, as before stated, it is not energizergl by this flow ofcurrent, but the ringdown relay 26 is energized and attracts itsarmature, thus closing a holding circuit for said relay from battery 49to ground at 44, which maintains a closed path for the illumination ofthe lamp 32 from a battery 43 to ground at 44 to notify the operator ofthe call, to which she will respond by depressing her listening key. Amultiple path is `thus provided for the ringing current through thecontacts of the listening key 29, conductor 33, through the bridge 45,including condenser 35 and relay 34, and back over the other side of theline by way o't conductor 33, contact of key 29, to conductor 4l andground at 27 over the path previously traced. The relay 34 is nowoperated and closes at its front contact the loW resistance pathincluding resistance 35a, Which allows of an adequate increase in thecurrent flow tor the energization of the marginal relay 38 at the Aboard, Which thereupon attracts its armature 24a and breaks the shortcircuit ot relay 20, Which is then energized and attracts its armature,thus breaking connection with its back contact and making connect-ionwith its front contact which places a short circuit about niagnet 17,and locks itself up in a circuit which may be traced from the groundedarmature 10. conductors 11. 13. the relay itself, its armature and frontcontact. conductor 48 to thc grounded battery 1f). The relay 17 beingnow denergized, allows` its armatures 24, 25 to make connection withtheir back contacts which lead to the terminals of a battery 40 bridgedacross conductors 45` 46 through the usual repeating coil 47. Currentfrom said battery now flows out over the trunk line and may be tracedfrom the free pole of said battery, repeating coil 47, conductor 46,including relay 8, back contact of armature 24, conductor 2, ring of theplug, ring of the jack` conductor 4, contact of key 29, conductor 33,resistance 35a, retardation coil 41, relay 36, conductor 33, contact ofkey 29, conductor 4a, tip of the jack, tip of the plug, conduct-0r 1,armature 25 and its back contact, conductor 45, repeating coil 47 to theopposite pole of battery 40. The relay 36 is now operated and attractsits armatures thus bringing the operators telephone set into the circuitjust traced. The relay 8 is in the circuit just traced and is adapted tobe energized to attract its armature, thus shunt'ing out the lamp 7which will indicate to the calling operator that the call has beenanswered. The sequence of operations just traced occurs should theoperator at the desk position depress her listening key during aringing` interval. The operation ot the circuit, should the operatordepress lier listening' key during' a silent interval, will now beexplained. As before stated, during the silent interval direct currentfrom the source et current Q2 is being impressed upon the line. Thissource oit' current may in practice be approximately llO volts. Therelay 3S is wound to respond to current trom said source. It will hereadily apparent theret'oi'e that should the answering operator depressher listening key during a silent intei-val` the relay 3G willimmediately be enerlized and attract its armatures, thus bringingr theoperators telephone into circuit, current from the same soui'cc,l'ioweii'er, havino, already energized relay 3S which attracts itsarmature 2st causing the energization ot relay 20, which attracts itsarmature and short circuits relay 17, the latters armature 24 thereupondisconnecting itself from the lead to the source of ringing current andcompleting, with armature a circuit to the answering` board includingthe source of current 40 to hold up relay BG. YUpon the taking down ofthe Connection at the desk operators position, the circuit ot relay 8will again be broken and its armature will fall back removing the shunt9 about lamp 7 and thereby causing, its illumination to notify the Aoperator ot the termination of the call, 'when she will withdraw theplug from the trunk ack, whereupon the apparatus will he restored tonormal.

lVhile for convenience of illustration, several batteries are shown itwill of course be understood that these sources of current, 7here theyare of the same polarity and located in the same exchange, may he, andin practice are one and the same battery.

Having thus described my invention, I claim 2- il. The combination withan electric circuit and means for supplying.y ringing current at onepoint in said circuit. of an electro-resphnsive device included in saidcircuit at another point, automatic means actuated upon the response ofsaid device to said ringingJ current todisconnect-said ringing currentfrom said circuit, a source'of direct current, telephone apparatusnormally disconnected from said circuit, and means responsive to saiddirect'current after cessation ot said ringing' current tiow in saideircuit to connect said telephone apparatus thereto. D

2. The combination lwith an electric cirltelephonie apparatussubstituting a source of cuit, of a source ot current, means forapplying said current to said circuit, a relay, a. switch adapted toinclude said relay in said circuit, a second relay actuated in theresponse ot said first mentioned relayifor disconnecting said source ofcurrent from said circuit, telephonie apparatus, anda switch actuated inthe response Y'ot said irst mentioned relay adapted to connect saidtelephonie apparatus in circuit, whereby the is not connected in circuituntil said source of current has been disconnected.

3. The sw-itcli-l'ioard, ot an electric circuit associated therewith, asource of ringingr current, nipans 'for applying said current to saidcircuit. an electro-responsive device included in said circuit, meansactuated upon the response ot said device to said ringing current todisconnect said ringing current from said circuit, a source ot directcurrent, telephone apparatus normally disconnected from said circuit,and means responsive to said direct current after cessation of saidringing cur-` conneet said tele` rent tlow in said circuit to phoneapparatus thereto.

The combination avith two switchhoards. ot' a circuit connecting saidswitclihoards, a source oi' ringingr current, nieans at one of saidswitchboards Jfor applying' said ringing current to said circuit, anclcctro-responsive device included in said circuit at the other of saidswitchboards, means actuated by said ringingf current in said circuitupon the response of said device thereto to disconnect said ringingJcurrent 'from said circuit, a source of direct current, telephoneapparatus Vnormally disconnected il'rom said circuit. and meansresponsive to said direct current a'tter cessation of said ringing;current tlow in said circuit to corinect said telephone apparatusthereto.

5. The combination with two telephone switchboards, connected togetherby a pair ot' conductors, means at one ot'said boards adapted tocomplete a` circuit for said con ductors and to apply ringing currentover said conductors to said other board. a signal operated thereby, alistening,lr key adapted to be depressed in response to said signal, an

to include a relay in said circuit,l the response ot said relaycausing.,Y the disconnection ot the ringing,r current from the circuitand the inclusion ot an operators telephone set therein.

'6. 'lhe combination with anV electric circuit, of a source ot ringing,rcurrent, means 'for applying.: said ringing current to said circuit, aswitch, a relay responsive to the closure ot said switch, means actuatedupon the response ot saidv relay tor disconnectingv said ringing currentfrom said circuit and direct current there- ;tor, telephonie apparatus,and means actutelephone combination. with a telephoneated by' saiddirect current for includingf said telephonie apparatus in said circuit.

7. rilhe combination With an electric circuit, a -sourceoiring'ingcurrent, means for applying` said ringing' current to said circuit, aswitch, a relay responsive to the elosure, of said switch, said relay inits response causing the disconnection of said ringing current from saidcircuit and the substitution of direct current therefor, telephonieapparatus, and a relay actuated by said direct current ior including'said telephonie apparatus in said circuit.

The combination with a calling switchboard A, an answering switchboardB, and a telephone trunk line uniting' said switchboards, a source ornringing current at said A board, means for applying' said current oversaid trunk to the said B board, means at the A board operative upon theactuation of said switch for disconnecting said ringing current from thetrunk line and substituting direct current therefor, a normally opencircuit at the B board including an operators telephone set, and meansactuated by 'said direct current for closing said circuit through saidtrunk line.

9. The combination With two telephone switchboards at each of whichtelephone lines are Centered, of a trunk' line uniting saidswitchboards, a source of ringing current at one of said boards a signalat the other board, means for applying` said current to said signal, aswitch adapted to be actuated in response to said signal, a relay atsaid last mention d board adapted to be energired by said ringingcurrent upon the actuatic n ot' said switch and adapted te close a lowresistance path. for said current, an electrically controlled switch atthe first mentioned board, the resultant increase in current causingsaid electrically controlled switch to disconnect said ringing currentfrom the line and substitute tl'ieret'or direct current, an operator-stelephone set in a nor- B boa-rd, a switch at mally open circuit at saidlast mentioned board, and a relay thereat adapted to be enenergized bysaid direct current to close said circuit through said trunk line.

l0. ri`he combination with two telephone switchboards at each of whichtelephone lines are centered, a. telephone trunk line uniting' saidboards, a ringing generator at one of said boards, a Signal at the otherboard, means for applying current from Said generator to said trunk lineto operate Said signahui listening key, a relay at said lastnientionedboard energized upon the depression of said listening key, and arrangedto close a low resistance path for said current, the resultant inrrcasein current serving to operate means at said first-mentioned board fordisconnecting" the said generator from the line and substituting' asource of direct current therefor, an operators telephone set in anormally open circuit at said other board the leads to said circuitbeing ar-.

ranged 'to be connected in the circuit ofy the trunk line by anelectromagnetic switch actuated by said direct current.

il. The combination with two telephone switchboards at each oi whichtelephone lines are centered, of a trunk .line uniting said boards,means at one of said boards for applying ring-ing current over saidtrunk line tothe other ated by the operator at that board fordisconnectingl said ringing,r current from the line and substitutine`direct current therefor, and an electrically operated switch at Saidlast inlined board. responsive to said HOW of direct current, foruniting to said trunk line a circuit including an operators telephoneset.

In Witness whereof, l hereunto subscribe my name this eighteenth day ofDecember A. D. 1909.

, SAMUEL B. W1 LlAMS.

Witnesses:

InviNo ldliCDonmLnD llnuAu F. BnAUnn-m.

board, and a switch actu--

